The present invention relates generally to fuel tanks for vehicles and, more particularly, to a fuel permeation barrier fuel tank for a vehicle.
It is known to provide a fuel tank such as a plastic fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. When a plastic fuel tank is made, a weld line is formed by the co-extrusion of a multi-layer parison and blow molding it to form the tank, or when sheets are co-extruded, vacuum formed into two shells, and welded together to form the tank. In most cases, one of the co-extruded layers is a material that acts as a barrier to prevent excessive permeation of fuel into the atmosphere. One concern with plastic fuel tanks is that exposure to sources of radiant heat could soften the walls, compromising the structural integrity of the fuel tank, or lead to excessive internal pressures by heating the fuel.
One commercial approach to resolve this concern is to thicken the barrier layers or add addition barrier layers in the walls of the fuel tank, which increases the weight, cost and reduces fuel capacity of the fuel tank. Another commercial approach is to protect the fuel tank by metal sheets or insulating heat shields, which increases the weight and cost of the plastic fuel tank. A further commercial approach is to use active cooling, which is complex and costly.
Therefore, it is desirable to provide a fuel tank for a vehicle that has a more effective fuel permeation barrier to prevent evaporative emission. It is also desirable to provide a fuel tank for a vehicle having all or part of the fuel tank encased with a film of reflective material to protect the underlying structure in a plastic fuel tank.
It is, therefore, one object of the present invention to provide a new fuel permeation barrier fuel tank for a vehicle.
It is another object of the present invention to provide a fuel tank encased in all or part of film of reflective material to protect the underlying structure.
To achieve the foregoing objects, the present invention is a fuel permeation barrier fuel tank for a vehicle including a tank shell having a wall formed from a plurality of layers. The layers include at least an inner layer, an outer layer, a fuel permeation barrier layer disposed between the inner layer and the outer layer, and a thermoformable layer disposed adjacent the outer layer to improve permeation resistance and protection against radiant environmental heating of the fuel tank.
One advantage of the present invention is that a fuel permeation barrier fuel tank is provided for a vehicle that has a more effective fuel permeation barrier leading to less evaporative emission. Another advantage of the present invention is that the fuel permeation barrier fuel tank uses a thermoformable film applied to portions of the fuel tank wall improving product quality, by decreasing fuel tank temperature, and improving fuel barrier properties. Yet another advantage of the present invention is that the fuel permeation barrier fuel tank reduces heat and fuel permeation in a plastic fuel tank without adding complexity, weight, or increased cost.